1. Industrial Useful Field
This invention relates to a so-called flat-type torque converter having a small axial thickness, and especially to an improvement in passage shapes of a turbine, a pump and a stator and a shape of a stator blade.
2. Prior Art
Generally, a torque converter forms a toroid wherein fluid circulates througe a turbine, a pump and a stator, and it is an important condition for maintaining a good torque converter efficiency to preset a passage cross section to an approximately constant value over the entire region of the toroid and to preset a velocity component of circulating fluid along a plane including an axis of rotation (abbreviated to a meridian plane component, hereunder) to a constant value over the entire region of the toroid.
In recent year a flat-type torque converter having a small axial thickness has been developed. As for this flat-type torque converter, a prior art (Examined Japanese Patent Publication No. 57-37791) is well known, wherein a flow turbulence of circulating fluid inside the toroid is reduced by throttling a passage cross section of toroid to some extent in its way, for example.
In such the prior art, however, the passage cross section is throttled in its way so that a passage resistance increases to make it difficult to preset shapes of the turbine, the pump and the stator.
Further, a prior art (Unexamined Japanese Patent Publication No. 58-152965) is well known, wherein passage cross sections are kept constant for the turbine and the pump, and a passage cross section is throttled in its way giving prominence to the uniformalization of said meridian plane component as for the stator.
In such the second prior art, however, a passage resistance at the stator section increases to make it difficult to preset a shape of stator.